Method for operating a flowmeter and flowmeter

A method for operating a flowmeter having at least one diagnostic unit, a counter unit and a storage unit with at least one memory for carrying out a plurality of time-limited measuring operations during which the counter unit determines at least the overall volume of a fluid passing through the flowmeter during one measuring operation. The counter unit is operated for the duration of a time-limited measuring operation, and the diagnostic unit recognizes at least one erroneous or error-free state of the flowmeter. The method ensures a particularly high reliability of the measured values determined during an individual measuring operation by the diagnostic unit generating at least one status message based on the state that is transmitted to the storage unit and stored in the memory, and by several status messages being transmitted and cumulatively stored in the memory at least for the duration of the measuring operation.